Elastic-fluid turbine.



No. 809,816. PATENTED JAN. 9, 1906. A. H. KRUBSI.

ELASTIC FLUID TURBINE.

APPLICATION FILED JULY 29, 1904.

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No. 809,816 PATENTED JAN. 9, 1906.

A. HLKRUESI. ELASTIC FLUID TURBINE.

APPLICATION FILED JULY 29, 1904.

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UNITED STATES PATENT. OFFICE.

AUGUST H. KRUESI, OF SCHENECTADY, NEW YORILASSIGNOR TO GEN- ERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK- ELASTIC-FLUID TURBINE.

No. 809,8 1e.

Specification of Letters Patent.

Patented Jan. 9,1906.

Application filed July 29, 1904. Serial No. 218,604.

To (l/Z Z/ whmit it ntay concern:

Be it known that I, AUGUST H.,KRUEsI, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Elastic-Fluid Turbines, of which the following is a specification.

This invention relates to turbine-engines operated by heated elastic fluid, such as steam; and its object is to enable the clearance between the revolving buckets and the stationary intermediates to be reduced, so as to lessen the leakage of steam.

The shell or casing of a steam-turbine is comparatively thin and of large surface, so that when steam is turned into it the result.- ing expansion takes place quite rapidly. The shaft, on the other hand, is quite thick and of considerable mass in proportion to its surface. It therefore absorbs heat more slowly and requires a longer time to reach the same final temperature as the casing and the same resultant amount of expansion. Since the intermediate buckets and the nozzles are secured to the casing, the more rapid expansion of said casing will cause them to interfere with the revolving buckets carried by the shaft unless enough clearance is provided between the two sets of buckets to allow for this relative movement. It follows that there will be more or less loss of steam through this clearance.

My invention aims to prevent this by so constructing the shaft as to expedite its expansion up to or approximately to the same rate as the casing. T 0 this end I make the shaft tubular or with longitudinal openings and provide means for admitting steam into it, so that it may become heated from within as well as from without. The steam may be admitted from each stage through ports in the shaft to the corresponding portion of the bore, or it may be admitted at first from the first stage to a longer portion of the shaft and be automatically shut ofl from all but the part corresponding with the first stage after the shaft has sufficiently warmed up.

In the accompanying drawings, Figure 1 is a longitudinal section of a four stage steam turbine embodying my invention. Fig. 2 is a similar section showing a modification, and Fig. 3 is an enlarged view of the automatic valve.

The turbine-casing 1 supports the nozzles 2 and the intermediate buckets 3. The shaft 4 carries the bucket-wheels 5, on which are mounted the buckets 6, revolving in close proximity to the nozzles and intermediates. The shaft has a central bore 7, which may be drilled in a solid shaft in case a tubular shaft is not suitable. It is connected with the several stages by ports 8 above and below the bucket-wheel in each stage. These ports permit the idle or inactive fluid in the space above the wheel or on the inlet side thereof to pass through the shaft to the space at the loweror exhaust side of the wheel of one stage or to pass from one stage to a succeeding stage. In other words, the fluid which escapes into the wheel-compartments through the clearance is made use of in heating the interior of the shaft. Thus it will be noted that the motive fluid in its normal path through the turbine is not interfered with, nor does it perform any part of the shaft-heating operation. The bore preferably decreases in diameter from the first stage to the last in order to lessen the heating effect, and thus produces a varied expansion corresponding with the decrease in pressure and temperature 6f the steam as it passes from stage to stage. As it would be wasteful of steam to permit it to flow through the bore 7 from the first stage directly to the last, plugs or diaphragms 9 are inserted in the bore between the several stages. It will therefore be seen that the portion of the shaft corresponding with each stage is subjected to steam of the same temperature, both internally and externally, as the corresponding portion of the casing, so that the expansion of both will be more nearly simultaneous.

In Figs. 2 and 3 I have shown a modified construction in which the central bore of the shaft is not permanently plugged between all the stages, but a thermostatic valve is used to shut off the flow of steam from the first stage to the second after the shaft has expanded to the same extent as the casing. The preferred form of thermostat is a thin steel tube 10, fixed at one end in a plug 11 between the second and third stages and carrying the valve 12 at its other end in cooperative relation with a seat 13 in the shaft. The tube is open at its upper end to admit steam to its interior, so that it will heat up quickly. Only one port is provided from each stage to the central bore of the shaft, and when the steam is turned on it can flow from the first stage to the second and from the third to the fourth. The thin tube 10 expands more rapidly than the massive shaft, and thus opens the valve and holds it open until the lengthening of the shaft brings the seat against the valve and closes the passage-way, after which the proper amount of expansion for each portion of the shaft depends upon the temperature of the steam in the adjoining stage. By thus producing a more rapid expansion of the shaft the danger of the wheelbuckets striking the intermediates is obviated and the clearance between the revolving and the stationary buckets can be reduced to a minimum.

In order to illustrate my invention, the clearance has been somewhat exaggerated, particularly between the valve 12 and its seat. It is obvious that the valve should close before the clearance between the relatively movable buckets becomes abnormally small on one side and abnormally great on the other.

My invention may be used with turbines having a different number of rows of wheelbuckets per stage or different nozzles or devices for admitting steam, also with other types of turbines wherein differences in expansion are to be accounted for.

In accordance with the provisions of the patent statutes I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof but I desire to have it understood that the apparatus shown is only illustrative and that the invention can be carried out by other means.

What I claim as new, and desire to secure by Letters Patent of the United States, is-

1. A turbine comprising a casing, a shaft therein which tends to expand less rapidly than the casing, sets of buckets on the shaft, devices for discharging motive fluid against the buckets, and ports in the shaft which are disposed out of the path of the fluid passing from one set of buckets to another for admitting fluid to the shaft to accelerate the heating and expansion thereof.

2. An elastic-fluid turbine which is divided into stages, each stage being provided with a Wheel-compartment, bucket-wheels in the compartments, a shaft for the wheels which tends to expand at a different rate from the walls of the stages, devices for admitting fluid to and directing its passage through the stages, and a means for causing the shaft to expand substantially with and at the same rate as the walls of the stages.

3. A turbine comprising stages, each stage having a wheel-compartment, bucket-wheels in the compartments, a shaft for the wheels extending axially through the stages which tends to expand at a different rate from the latter, discharging devices arranged to deliver motive fluid against the buckets and cause the fluid to traverse a path parallel to the shaft and adjacent the walls of the stages, and means for acting on the shaft in a manner to cause it to expand substantially simultaneously with and at the same rate as the stages.

4. A multistage turbine having a tubular shaft containing ports communicating with the several stages to permit the idle fluid therein to pass through the shaft from a point of high to a point of low pressure, and means for closing the bore of the shaft between two or more of said stages.

5. A multistage turbine having a tubular shaft containing ports communicating with the several stages, and means for automatically closing the bore of the shaft between two or more stages when the shaft has expanded a certain amount.

6. A multistage turbine having a tubular shaft containing ports communicating with the several stages, and a thermostatic valve for closing the bore of the shaft between two stages.

7. A multistage turbine having a tubular shaft containing ports communicating with the several stages, a thin metallic tube in the bore of said shaft, a valve carried by said tube, and a valveseat in the shaft.

8. A multistage turbine having a casing which expands more rapidly in the highpressure stages than in the low, a wheel-carrying shaft extending through the stages which is located out of the normal path of the motive fluid and tends to expand less rapidly than the casing, and a means for heating the portion of the shaft in the high-pressure stage or stages to a greater extent than the portion in the low-pressure stage.

9. A turbine comprising a casing, diaphragms therein which divide it into compartments, a shaft extending axially through the casing which tends to expand less rapidly than the latter, bucket-wheelS in the compartments which are carried by the shaft, and a conduit in the shaft which connects a point of high pressure in the casing with a point of low pressure for causing motive fluid to pass therethrough for heating the shaft to accelerate its expansion.

10. A multistage turbine, comprising a casing and a wheel-carrying shaft, one of which expands more rapidly than the other owing to the difference in surfaces exposed to the motive fluid, and a means which utilizes the idle fluid in one or more stages for subjecting one of said turbine elements to the heating effects of said fluid to reduce the tendency to unequal expansion.

In witness whereof I have hereunto set my hand this 28th day of July, 1904.

AUGUST H. KRUESI. l/Vitnesses:

BENJAMIN B. HULL, HELEN ORFORD. 

